Combustion Systems and Excess Air

Combustion is a chemical process that involves the reaction between fuel and an oxidizing agent, usually oxygen. The combustion of fuels releases energy in the form of heat, which can be used for various applications such as heating, power generation, and propulsion. However, combustion is not a perfect process, and it can produce harmful pollutants such as carbon monoxide, nitrogen oxides, and particulate matter. One of the ways to control these pollutants is to provide excess air during combustion.

Combustion systems are designed to optimize the combustion process and achieve the desired performance and emissions. Some of the common combustion systems include:

1. Pulverized coal combustion
2. Oil burners
3. Gas burners
4. Biomass combustion
5. Stoker-fired boilers

Excess air is the amount of air supplied to the combustion process above the theoretical air required for complete combustion. The excess air helps to dilute the pollutants and ensure that the combustion is complete. However, providing too much excess air can reduce the combustion efficiency and increase the energy consumption. Therefore, it is important to optimize the excess air for each combustion system.

Answer Explanation

The combustion system that requires maximum excess air is the chain grate stoker. A chain grate stoker is a type of solid fuel combustion system that uses a moving bed of fuel (such as coal or biomass) on a grate to supply the fuel for combustion. The excess air is required to ensure that the fuel is burned completely and to prevent the formation of harmful pollutants such as carbon monoxide and particulate matter.

The other combustion systems such as pulverized coal combustion, oil burners, and gas burners require less excess air because they have a more controlled combustion process. In these systems, the fuel is mixed with the air in a controlled manner, and the combustion is more efficient. However, even these systems require a certain amount of excess air to ensure complete combustion and prevent emissions.

Conclusion

In conclusion, excess air is an important parameter in combustion systems, and it is necessary to optimize it for each system. The chain grate stoker is the combustion system that requires maximum excess air, while other systems such as pulverized coal combustion, oil burners, and gas burners require less excess air. By optimizing the excess air, it is possible to achieve better combustion efficiency and lower emissions.